Induction relay



July 17, 1928.

S. L. GOLDSBOROUGH INDUCTION RELAY F iled May 25, 1925 WITNESSESATTORNEY Patented July 17, 1928 UNITED STATES PATENT oFFicE.

SHIRLEY L. eoLns oRoU Gn, or PITTSBURGH, PENNSYLVANIA,VASSIGNORVTO wEsT-menousn ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION or PENN-SYLVANIA.

INDUCTION RELAY.

Application filed May 25, 1925. Serial No. 32,544.

My invention relates torelays and particularly to relays of theinduction type.

One object oi my invention is to provide a reverse-energy relaythatshall have means 1 core member with projecting pole pieces on whichwindings aredisposed, the electrical and magnetic circuits arenecessarily unsymmetrical. to some extent. The efiect upon thecharacteristics of the relayis too slight to cause trouble in most typesof relays, but it cannot be ignored in the case of a reverseenergy relaywhich must operate over a wide range of currents.

It is often desirable to use a reverse-energy, relay for the protectionof a distribution system in which the short-circuit current may be tenor twenty times the normal full-load current. The relay is provided witha voltage winding and is designed to operate only whenthe flow of poweris in a predetermined direction. If the current winding of the relay orthe portion of the core member energized thereby is slightly unbalanced,it is evident that the effect of such unbalance becomes greater nndershort-circuitconditions,

particularly as a short-circuit is usually accompanied by 'aconsiderable reduction in system voltage. The result is that the relayoperates or does not operate, as the case may be, in a certaindirectiouwhen the current reaches four or five times the normal valueirrespective of the phase relation of the voltage, unless the relay isrelatively insensitive.

It has been found that the undesired characteristics of the relayresultfrom a number of causes, such as an unequal number of ampere-turnsupon the series pole pieces, an uneven air gap between the upper andlower po'le pieces, an armature that is not properly alined with respectto the pole pieces, and I equality in the resistances ofth'e electricalpaths in the laminated core member. As it' is impracticable to attempttocorrect each of these causes, I obtain the desired compensation bymodifying theflux traversing the armature from the series poles. Inaccordance'with my invention, an adjustable magnetizable shunt memberaround the armature is disposed adjacent to the series poles. Byadjusting this member, the flux traversing the armature may be soanodified that no torque is exerted on the same by the current windingalone even when the current is excesslve.

' Fora more complete understanding of my invention, reference should behad to the accompanying drawing, in which V Figure 1 is a diagrammaticview of a relay of the induction, type embodying my invention; and, f

Figs. 2, 3 and 4: are detail views of the magnetizable shuntmember shownin Fig. 1. Referring to Fig. 1, the relaycomprises a' magnetizable coremember 1 having windings 2 and '3 thereon and a movable armature member4 controlling the co-operating contact members 5'.

The relay shown is adapted to be used as a watt or reverse-energy relay,the winding 2-being connected in series and the winding 3 in .shunt withan alternating-current cir cuit. TheIcore member 1 comprises upper polepieces 6 andu'? and lower pole pieces-8,.

9 and 10. The series winding 2 is disposed upon the upper pole piecesand the shunt winding 3 on thelower pole piece '9.

l The armature member 4% is a pivoted'conducting disc disposed'in theair gap between the upper and the lower pole pieces and operated by themagnetic fluxes traversing this air gap and produced by the windings 2and 3. The armature member 4 should only be actuated when both windings'2 and 3 are energized and the direction and torque of the armaturemember should depend upon the value and the phase relation of thecurrents in said windings".

subjected to 100 volts.

It is found in practice, however, that the magnetic circuits of thewindings 2 and 3 are usually slightly unbalanced or the ampere turnsupon the upper pole pieces 6 and 7 are unequal so that a torque isexerted upon the armature member 4- when the winding 2 alone isenergized Other conditions may aggravate this effect, such as unequalair gaps between the upper pole pieces 6 and 7 and the lower polepieces, a faulty alinement ofthe armature member 4 in the air gap ortransverse electric circuits across'the laminatedfacesof the upper polepieces 6 and 7 that are of unequal resistance;

Since it is impossible to eliminate this unbalancing of the magnetic andelectrical circuits ofthe relay, I provide magnetizable shunt memberslland 12 mounted on the 'core member -1 adjacent to the upper pole pieces6 and 7 to compensate for the torque otherwise exerted on the armature,The shunt members 11 and 12 are pivoted, as shown iii Figs. 2 and 3,upon a bolt 13 and may be secured in adjusted position by means of alocking screw 1 1. As shown in Figs; 3 and 4, the shunt member 12comprises an L-shaped sheet-metal portion 15 riveted at 16 to aperforated sheet metal portion 17 that receives the bolt 13. The portion1770f the shunt member is perforated at 18 to receive the head 19 of thebolt 13,

the perforation 18 being large enough to permit slight relative movementof the shunt member about the bolt 13. Washers 20 and 21 are clampedbetween the portion 17 of the magnetizable shuntmember 15 and the coremember 1, the Washer 20 being threaded to receive the locking screw 14.

To adjust the relay, the series winding 2 is connected to a source ofcurrent and the voltage winding 3 is open-circuited. A current of 25 oramperes, which is five orten times the-normal value, is passed throughthe winding 2. The magnetizable shunt members 11 and 12 are thenadjusted until l balance and no ber 41 by the encrgization of thecurrent winding-alone. If the voltage Winding is then energized,'thedirection of the torque exerted upon the armature member 4; will dependsolely upon the phaserelation of the currents in the windings 2 and 3and the relay will operate properly, even when an excessive currenttraverses the winding 2 and only a small voltage is applied to thevoltagewinding 3. I

Under normal conditions, the ,current winding 2 may be traversed bythree amp'eres and the voltage winding 3 may be Under these conditions,the torqueexerted on the armature member 4 is in such a direction as tomaintain the contact members 5 open. When the flow of energy in thecircuit reverses, however, the phase relation of the voltage withrespect to the current changes and a torque is exerted upon the armaturemember 4 which tends toclose the contact members 5. Since ashort-circuit is usually accompanied by a drop in voltage, the relay maybe adjusted to operate even when the voltage appied to the winding 3 isreduced to 1 or 2 volts. Furthermore, although the short-circuit maycause the current winding 2 of the relay to be traversed by 50 or 100amperes, the relay will still operate in accordance with the directionof the flow of energy, since the effectof the current winding alone isaccurately compensated by the magnetizable shunt members ll and 12.,

I do not consider that my invention is limited to the precise form shownand described, as it may be applied to relays of other. types andthedetails of construction of the shunt member may be varied withoutdeparting from the invention. I do not 'WlSh to be limited in scope,therefore, ex-

cept as limitations may be indicated in the appended claims.

I claim as my invention:

1. Aninduction relay comprising a magnetizable core member having upperand lower pole pieces, a movable armature disposed betweensaid polepieces and a magnetizable shunt for said armature extending between anupper and a lowerone of said pole pieces. 7 i v 2. .An induction relaycomprisinga magnetizable core member having upper and lower pole pieces,a movable armature disposed between said pole pieces and an adjustable.magnetizable shunt for said armature extending between upper and lowerpole pieces and movable with respect to one of said pole pieces.

3, An induction relay comprising a ,magnetizable core member, currentand voltage windings thereon, a movable armatureac- ,t-uated thereby inaccordance with the phase relations of the currents traversing saidwindings and an adjustable magnetizable shunt about said armature andpivotally mounted upon the core member.

, 4. An induction relay comprising a mag-- netizable core member havingprojecting pole pieces, an armature member adjacent said pole pieces, anL-shaped magnetizab'le shunt member pivotally mounted on said coremember and controlling the flux traversing said armature member andmeans for securing said shunt member in desired position. F

5. An induction relay comprising a onepiece magnetizable core memberhaving upper and lower projecting pole pieces, an armature memberdisposed between said pole'pieces, and an Lshaped magnetizable shuntmember pivotally mounted on said core member on each side of said upperpole pieces and extending adjacent thereto.

6. An induction relay comprising a onepiece magnetizable core memberhaving two upper and a lower projecting pole pieces, an armature memberdisposed between said sets of pole pieces and means for so shunting themagnetic flux between the sets of pole pieces from the armature memberthat the armature is precluded from operating except by the cooperationof the magnetic flux produced by both sets of pole pieces.

In testimony whereof I have hereunto subscribed my name this 14th day ofMay, 1925.

SHIRLEY L. GOLDSBOROUGH..

